BIP32Key: make hard-coded constants into module constants
BIP32Key: make hard-coded constants into module constants

Signed-off-by: Johnathan Corgan <970c387dcb42498229f453ae092d0497276e2f9b@corganlabs.com>

satoshilabs/bip32utils,satoshilabs/bip32utils,prusnak/bip32utils,bitwolaiye/bip32utils,marcoslin/bip32utils,bitwolaiye/bip32utils,marcoslin/bip32utils,prusnak/bip32utils